Reply from Hosting provider was as follows.
"You are a reseller, so root access would never be given.
We suggest contacting Blesta support and letting them know you have a reseller account, not root access."
Should I give up on using this hosting provider's reseller account?
Or do I still have other worthy things to try?

Thank you.
But, ...
I think I don't have root access to the WHM server.
Because the following message was displayed.
"WARNING: The API Tokens with ACL restrictions feature is experimental."
What should I do in this cases?

Thank you.
I saw Tools > Logs: Module tab.
I attach a figure.
"Success" is displayed.
However, Output has the following display.
{"package":[]}
Does this indicate that I am not using "Root" users?
I am a Cpanel reseller, so I can not possibly use "Root" users. ( Am I wrong? )
Originally, I think whether selecting "Standard" or "Reseller" is an item of "CPANEL Package".
I also examined ACL.
ACL https://documentation.cpanel.net/display/DD/Guide+to+WHM+Plugins+-+Access+Control+Lists
Guide to WHM Plugins - Access Control Lists
Access Control Lists (ACLs) limit the features that WHM users can access. Each ACL represents permissions that the root user can grant to other WHM accounts (resellers
Server administrators can define ACLs in WHM's Edit Reseller Nameservers and Privileges interface (WHM >> Home >> Resellers >> Edit Reseller Nameservers and Privileges).
There is not this screen(WHM >> Home >> Resellers >> Edit Reseller Nameservers and Privileges) on my WHM screen.
Should I ask the hosting provider (resale source) for something?